The capuchin monkey, indigenous to Central and South America, is a
rather distant relation of humankind. We are Old World primates--more
closely related to chimpanzees, orangutans, and even baboons.
Nevertheless, we have much to learn from capuchins.
They are the largest-brained, smartest monkeys in the New World.
And they have independently evolved many traits--like tool use--that were once regarded as uniquely human.
Why? There are many reasons, but one of them should interest all
parents. Like people in many human cultures, capuchins are remarkably
tolerant of juvenile curiosity.
UCLA anthropologist Susan Perry has been watching wild capuchins for almost 20 years—ever since she founded the Lomas Barbudal Capuchin Monkey Project in Costa Rica. She's observed monkeys from infancy to adulthood, tracking what juveniles learn as they grow up. Along the way, she and her colleagues have documented some remarkable similarities between capuchins and humans (Perry and Manson 2008).
These large-brained, social monkeys
• Use tools to get food. Like humans, capuchin monkeys are omnivores, and many of the foods they eat require mechanical processing—like pounding, prying, or scrubbing. To be an effective forager, a young capuchin monkey must learn how to tackle each food type. In some cases, capuchins actually use tools—like a hammer stone to open a nut or seed.
• Share. Experiments show that capuchins will spontaneously share treats with familiar group members (deWaal et al 2008). Capuchins share food in the wild, too, and show more spontaneous prosocial behavior than do chimpanzees (Burkart and van Schaik 2012; Sabbatini et al 2012).
• Use “daycare." After a capuchin monkey infant is born, group members compete for a “turn" with the baby, inspecting and handling it whenever the mother permits. As babies become more independent, they initiate these interactions. Non-maternal “babysitters" may carry babies up to 9% of the time. And babies are regularly nursed by females other than their own mothers (Perry and Manson 2008).
• Form friendships, alliances, and social cliques. Capuchins don’t just make friends. They also know something about the friendships between other monkeys. For example, consider this scenario: You are about to get into a fight. You look around to see if there are any people nearby who could help you. Whom should you ask for help? You might pick your closest available buddy. But what if that person is also friends with your opponent? Wild capuchins seem to think about these complications. In an analysis of 110 real-life capuchin monkey battles, researchers confirmed that monkeys don’t just pick their best friends. Rather, they solicit aid from individuals with whom they are better friends than their opponents are (Perry et al 2004).
• Learn to use “words." As she grows up, a young capuchin monkey needs to learn several different “words," or alarm calls that warn group members about the presence of predators. One call seems to mean “Look out, it’s a dangerous bird!" Other calls are about dangerous humans, cats, or snakes. It’s pretty clear that monkeys have to learn these meanings because kids make mistakes. About 20% of juvenile alarm calls are made in response to inappropriate targets. As kids get older, their alarm-calling becomes more accurate (Perry and Manson 2008).
Parents will recognize some other behaviors, too—like nipple tweaking. While nursing, an infant capuchin monkey doesn’t just drink milk. He also “preps" the other nipple, by kneading it with his hand. This stimulates milk production, and it seems to have a calming effect.
But one of the most surprising discoveries concerns social traditions.
Perry and her colleagues have discovered that some wild capuchin
groups engage in strange social rituals, like “hand sniffing," in which a
monkey slips its finger over—or inside—another monkey’s nose.
It’s not just a random act. When hand sniffing, the normally
boisterous monkeys are very quiet and still, sometimes for as long as
ten minutes. Monkeys are more likely to engage in hand sniffing with
their favorite grooming partners, and partners typically play both
roles—by taking turns or putting their fingers in each other’s nostrils
Perry suspects that these rituals function as many human rituals
do--opportunities to demonstrate commitment to each other (Perry and
How kids learn: Do capuchins have culture?
It seems that capuchin babies have a lot to learn--about tool use,
politics, predators, and social relationships. Do they have to learn it
all by themselves, or do they get a little help from their friends?
Humans take culture for granted. Kids don’t have to reinvent the
wheel every generation. They learn from us. Have capuchins evolved the
capacity for culture? Perry thinks they do.
For example, capuchins can open the edible seeds of the Luehea
fruit in one of two ways—by pounding or scrubbing. Both ways are equally
effective, but young monkeys eventually settle on just one
technique—whichever technique they’ve most frequently observed other
monkeys using (Perry 2009).
These findings are supported by experiments on captive capuchins.
In one study, researchers presented a capuchin monkey with a box that
could be opened in two ways—by lifting or sliding a door.
The monkey was trained to get food from the box using just one method.
Then he was paired with a naïve monkey—somebody who had never seen the
Despite being free to open the box anyway he liked, the observer
monkey showed a strong preference for the demonstrator’s method. When
the observer was subsequently paired with another “new" monkey, this
newcomer also preferred to use the method he’d seen modeled. In this
way, the capuchins spread a “tradition" along a chain of up to 5
observers (Dindo et al 2007).
So it appears that capuchins really do transmit something akin to
culture—learned behaviors that are passed from monkey to monkey. It
even seems that capuchins “learn from the best." A study of
nut-cracking--in which wild capuchins use stone tools to open
nuts--found that juveniles were more likely to watch the most proficient
nut crackers (Ottoni 2005).
So why are capuchins like humans?
Why is the capuchin monkey so similar to humans? Some similarities
reflect our common ancestry. For instance, it seems likely that mammal
babies have been kneading their mothers’ nipples for millions of years.
But the last common ancestor of humans and capuchins lived over
30 million years ago. It was small-brained and rather lemur-like.
similarities—like large brains, tool use, and high social
intelligence—were probably not present in the last common ancestor of capuchins and humans.
Instead, these traits evolved independently, after our lines diverged—like two separate experiments with similar outcomes.
The phenomenon is called convergent evolution, and it makes
capuchins especially useful. That’s because cases of convergent
evolution permit us to test hypotheses about the conditions necessary
for traits to evolve. What’s the common denominator linking each case?
For example, what can explain the evolution of tool use? If you
take a look at the primate family tree, it appears that the capacity for
tool use has evolved at least three times—once in apes (a group that
includes humans and chimpanzees), once in baboons and their close
relatives (the cercopithecine monkeys) and once in capuchins (van Schaik
et al 1999).
What do tool-using primates have in common? Yes, they are all
dexterous. And they tend to eat foods that need to be extracted or pried
But the most frequent tool users have something else in
common--something that’s a little less obvious: They are socially
Social tolerance: The key to tool use and social learning?
Picture this: A monkey invents a new tool or a new way to get food. Does anybody else learn the new trick?
For animals to learn from each other, they have to get close
enough to see what’s going on. And they can’t do that if everybody is
uptight, nervous, or unfriendly.
So researchers like Carel van Schaik have argued that social tolerance is a prerequisite for socially-transmitted tool use.
Tool use is more common in primate societies that are “laid
back," societies where dominant individuals are more tolerant of
subordinates, where individuals reconcile after conflicts, and where
adults allow juveniles to get close and observe what they are doing (van
Schaik et al 1999).
Capuchins fit this model well. Although capable of violence,
capuchins are also very tolerant of nosy youngsters. And the kids are
very nosy indeed. It’s not unusual for juveniles to sit alongside an
adult who is processing food, their eyes glued to the action. The kids
will watch with great intensity while the adult works—plenty of
opportunity to observe technique.
Does it apply to humans? It certainly seems to. A recent analysis
of over 80 years of research on classroom learning reveals that kids
tend to learn better in cooperative, noncompetitive settings (Roseth et
al 2008). So perhaps social tolerance was what gave our ancestors—and
the ancestors of apes, baboons, and capuchins—the edge.
Much more to learn—if we can keep the research going...
And public support has already made a big difference.
Currently, Susan Perry’s team is in the middle of a long-term study
of infant development--a study that examines how social factors
influence what capuchins learn about food, predators, and politics.
The study is very promising, because Perry’s team already knows
so much about the individuals and the groups they live in. The Lomas
Barbudal project has collected over 60,000 hours of behavioral
information, as well as genetic profiles and hormonal data.
But what about the future? Will research get derailed by destruction of monkey habitats? Poaching?
When I first wrote this article in 2009, the Lomas Barbudal
monkeys were under threat. Forest was being destroyed, and poachers were
Now there is good news. Strong advocacy and letter-writing campaigns have stopped the destruction.
On July 23, 2010, the Costa Rican park service and several
private organizations will sign an agreement promising future protection
for the capuchins. Perry and her team have gotten permission to
re-forest the area damaged by mining, and they've received large
donations of trees from government and private tree nurseries to begin
Interested in the project?
The monkeys' future is looking much brighter than it did in 2009. But
it's not too late to contribute. The Lomas Barbudal Monkey Fund aids
research, educational outreach, and local conservation. You can make a
Perry’s capuchin monkey webpage at UCLA.
Written with co-researcher Joe Manson,
this book combines theoretical discussions with detailed accounts of the
monkeys' daily lives.
The book is especially valuable for its frank depiction of the
challenges and frustrations of fieldwork. Want to know how field workers
collect their data? Eat? Sleep? Raise families while watching wild
animals? Perry and Manson answer these questions with vivid detail and wry humor.
References: The capuchin monkey
Burkart JM and van Schaik C. 2012. Group service in macaques (Macaca
fuscata), capuchins (Cebus apella) and marmosets (Callithrix jacchus): A
comparative approach to identifying proactive prosocial motivations. J
Comp Psychol. 2012 Jan 16. [Epub ahead of print]
deWaal, F, Leimgruber K and Greenberg AR. 2008. Giving is self-rewarding for monkeys. PNAS 105(36): 13685-13689.
Dindo M, Theirry B and Whiten A. 2007. Social diffusion of novel
foraging methods in brown capuchin monkeys (Cebus paella). Proc. R. Soc.
B. 275: 187-193.
Ottoni EB, de Resende BD, Izar P. 2005. Watching the best
nutcrackers: What capuchin monkeys (Cebus apella) know about others'
tool-using abilities. Anim Cogn 24:215-219.
Perry S, Barrett HC, and Manson JH. 2004. White-faced capuchin
monkeys exhibit triadic awareness in their choice of allies. Animal
Perry S. 2009. Conformism in the food processing techniques of
white-faced capuchin monkeys (Cebus capucinus). Animal Cognition. May 20
2009 (Epup ahead of print].
Perry S, with Manson J. 2008. Manipulative monkeys: The capuchins of Lomas Barbudal. Harvard University Press.
Roseth CJ and Johnson DW, and Johnson RT. 2008. Promoting Early
Adolescents' Achievement and Peer Relationships: the Effects of
Cooperative, Competitive, and Individualistic Goal Structures.
Psychological Bulletin 134(2):223-246.
Sabbatini G, De Bortoli Vizioli A, Visalberghi E, and Schino G.
2012. Food transfers in capuchin monkeys: an experiment on partner
choice. Biol Lett. 8(5):757-9. doi: 10.1098/rsbl.2012.0534.
Van Schaik CP, Deaner RO, and Merrill MY. 1999. The conditions
for tool use in primates: implications for the evolution of material
culture. Journal of Human Evolution 36: 719-741.